Linux change java home

How to Set JAVA_HOME Variable Path on Ubuntu

Basically, the JAVA_HOME Environment path points to the installation location of JDK (Java Development Kit) on your Ubuntu system.

As you develop or run Java-based applications, the associated applications sometimes need to know/reference the JAVA_HOME Environment path to execute/compile without any issues.

Before addressing this Java environment path issue, we need to revise the steps that might/have led us to this article’s objective. We need to start with understanding Java, and its installation, and finally addressing the JAVA_HOME path issue.

Understanding Java

Java has engraved its name in the programming languages’ hall of fame due to its contribution to reputable application footprints and they include:

• Creation of enterprise software.
• Scientific computation.
• Programming of hardware devices.
• Development of several modern Android applications.
• Development of mobile java applications.
• Developer and Big data analytics.
• Server-side technologies like Apache, GlassFish, and JBoss draw inspiration from Java.

Java Programming Language Superiority

Java is associated with several attributes that have contributed to the bold milestones that have made it successfully achieve the above-mentioned strides. The following factors have contributed to the superiority of Java as a programming language:

• It keeps evolving despite being mature.
• It is platform-independent.
• It simplifies real-time software development.
• Facilitates embedded computing.
• Supports IoT (Internet of Things).
• Simplifies and improves custom Big data solutions.
• Curtails project overheads.
• Enriched with library frameworks, IDEs, and development tools.
• Equipped with a rich set of APIs.
• It is recommended by Google for Android App Growth.

Java’s Main Components

Java is made up of three main components:

1. Java Virtual Machine (JVM) – It provides a runtime environment for bytecode execution. It entails specification (JVM’s implementations document), implementation (JVM specification’s requirements program), and runtime instance (needed when writing and running the class-associated commands on the system terminal).
2. Java Runtime Environment (JRE) – Meets the needed software/program execution requirements like supportive files and class libraries before the associated bytecodes are executed.
3. Java Development Kit (JDK) – The tools that make up the JDK are Compile, Document, and Package Java Programs. In summary, JDK is responsible for compiling, documenting, and packaging a Java program.

Java Program Execution

The final milestone of understanding Java is comprehending its program execution steps.

Three steps are involved in Java program execution:

1. Using an editor or IDE to write Java code. The final source code is saved in a file with an .java extension e.g sample_file.java.
2. Java code compilation via a Java Compiler. Write code is translated from source code to machine code e.g javac sample_file.java.
3. Execute/run the compiled machine code via Java Runtime e.g java sample_file.

Installing Java and Javac in Ubuntu

A Java Runtime Environment (JRE) like OpenJDK and Java compiler (javac) is needed for you to be able to run Java-based programs.

$ sudo apt install openjdk-17-jre-headless -y $ sudo apt install openjdk-17-jdk-headless $ java --version $ javac --version $ which javac

Set JAVA_HOME Path on Ubuntu

Locate Java’s installation directory:

Temporarily Set JAVA_HOME in Ubuntu

To temporarily set the JAVA_HOME path in Ubuntu.

$ export JAVA_HOME="/usr/lib/jvm/java-17-openjdk-amd64" $ echo $JAVA_HOME

Permanently Set JAVA_HOME in Ubuntu

To permanently set the JAVA_HOME path, add the above line in the /etc/environment file.

JAVA_HOME="/usr/lib/jvm/java-17-openjdk-amd64"

To permanently set the JAVA_HOME path to ~/.bashrc file, which gets executed every time a user starts a new terminal session.

Add the highlighted line at the end of the file:

export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64

Close the file and activate the changes:

Globally Set JAVA_HOME in Ubuntu

To globally set the JAVA_HOME path for all Ubuntu users, edit /etc/bashrc file:

export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64

Close the file and activate the changes:

Confirm that the JAVA_HOME variable is still set:

We have understood how Java works and how easy it is to set the JAVA_HOME path on Ubuntu.

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How to Set JAVA_HOME Variable in Ubuntu Linux Correctly

If you are running Java programs on Ubuntu using Eclipse, Maven or Netbeans etc, you’ll need to set JAVA_HOME to your path. Otherwise, your system will complain that “java_home environment variable is not set”.

In this beginner’s tutorial, I’ll show the steps to correctly set Java Home variable on Ubuntu. The steps should be valid for most other Linux distributions as well.

The process consists of these steps:

• Making sure Java Development Kit (JDK) is installed.
• Finding the correct location of JDK executable.
• Setting the JAVA_HOME variable and making the change permanent.

Step 1: Check if JDK is installed

The simplest way to check if Java Development Kit (JDK) is installed on your Linux system is by running this command:

The above command checks the version of Java compiler. If it is installed, it will show the Java version.

If the command shows an error like javac command not found, you’ll have to install JDK.

If Java Compiler is not installed on your system, install Java Development Kit using this command:

sudo apt install default-jdk

This will install the default Java version in your current Ubuntu version. If you need some other specific Java version, you’ll have to specify it while installing Java on Ubuntu.

Once you have made sure that Java Compiler is present on your system, it’s time to find its location.

Step 2: Get the location of JDK executable (Java Compiler)

The executable is usually located in the /usr/lib/jvm directory. I won’t left you on your own for a guessing game. Instead, let’s find out the path of the Java executable.

Use the which command to get the location of Java Compiler executable:

The problem here is that the location it gives is actually a symbolic link. You’ll have to follow it a couple of times:

And when you find a path like /usr/lib/jvm/java-11-openjdk-amd64/bin/javac, you remove the /bin/javac from it to get something like /usr/lib/jvm/java-11-openjdk-amd64

An easier method is to follow the symbolic link and get to the actual executable file directly using this command:

readlink -f `which javac` | sed "s:/bin/javac::"

The readlink command follows a symbolic link. I have used ` around which java. This is called command substitution and it replaces the command with its output. Sed is then used to replace /bin/javac by nothing and thus removing it altogether.

In my example, the location of the executable file is /usr/lib/jvm/java-11-openjdk-amd64. It could be different for you. Copy the correct path you got from the above command in your system. You know, you can copy paste in the Ubuntu terminal.

Step 3: Setting JAVA_HOME variable

Now that you have got the location, use it to set the JAVA_HOME environment variable:

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64/bin/java

Check the value of JAVA_HOME directory:

Try to run your program or project in the SAME TERMINAL and see if it works.

This is not over yet. The JAVA_HOME variable you just declared is temporary. If you close the terminal or start a new session, it will be empty again.

To set JAVA_HOME variable ‘permanently’, you should add it to the bashrc file in your home directory.

You can use the Nano editor for editing files in the Linux terminal. If you do not want that and take a simple copy-paste approach, use the following commands:

Back up your bashrc file (in case you mess it, you can get it back):

Next, use the echo command to append the export command you used at the beginning of this section. Change the command below to use the correct path as displayed by your system in.

echo "export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64" >> ~/.bashrc

Verify that it has been correctly added to the end of the file:

The above tail command will show the last 3 lines of the specified file.

Here’s the entire output of the above three commands.

Now, even if you exit the session or restart the system, the JAVA_HOME variable will still be set to the value you specified. That’s what you want, right?

Do note that if you change the default Java version in the future, you’ll have to change the value of JAVA_HOME and point it to the correct executable path.

I hope this tutorial not only helped you to set Java Home, it also taught you how you are doing it.

If you are still facing issues or have any questions or suggestions, please let me know in the comments.

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How to Set JAVA_HOME Path in Ubuntu 20.04 and Ubuntu 22.04

Many Java-based programs require the Java Runtime Environment (JRE) to run smoothly regardless of the operating system. For development, most IDEs like Eclipse and NetBeans require the Java Development Kit (JDK) on your computer. Whether you’re a newbie who wants to learn how to develop or an application you have installed requires a Java installation on your system, we’ve got you covered. Setting up the JAVA_HOME path is quite simple.

In this tutorial, we will learn how to install the JDK on Ubuntu 20.04 and Ubuntu 22.04 and set up the Java_HOME path. Let’s start with the installation of the JDK.

Install OpenJDK on Ubuntu

Note: Make sure that you have updated the Advanced Package Tool (APT) before you move forward to install OpenJDK.

Press Ctrl + Alt + T to open the terminal and enter the following command mentioned in the box. You can either install OpenJDK 8 or the newer versions OpenJDK 11 to OpenJDK 18. Not all versions are available on any Ubuntu version, you can check for available versions with the command:

Install OpenJDK 8

sudo apt install openjdk-8-jdk

Install OpenJDK 11

sudo apt install openjdk-11-jdk

Install OpenJDK 14

sudo apt install openjdk-14-jdk

Install OpenJDK 16

sudo apt install openjdk-16-jdk

Install OpenJDK 17

sudo apt install openjdk-17-jdk

Install OpenJDK 18

sudo apt install openjdk-18-jdk

You will be prompted to enter your sudo password to continue with the installation.

Once you’ve entered that, wait for the system to finish the installation and then move on to step 2.

Set JAVA_HOME Path

All you have to do now is to set the “JAVA_HOME” and “PATH” environment variables and then you are done. Enter the following commands to set your environment variables. Make sure that your environment variables point to a valid installation of JDK on your machine. For Ubuntu 18.04, the path is /usr/lib/jvm/java-8-openjdk-amd64/

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

To check whether your JAVA_HOME path has been successfully saved, enter the following command to check.

The value stored in the JAVA_HOME variable will be displayed on the terminal as you can see in the screenshot

Add JAVA bin directory to the PATH variable

Like we have added JAVA_HOME path, we will now update the PATH variable as well. To do that, enter the following command on the terminal.

export PATH=$PATH:$JAVA_HOME/bin

This will append the java bin directory to the existing PATH variable. You can also check the PATH variable by entering the following command

Test JAVA setup

You have successfully installed OpenJDK on your machine. You can verify your installation by entering the following command on your terminal.

Through this simple tutorial, you have now configured the JAVA_HOME variable in your operating system. You can now easily run java based applications as well as development environments on your machine.

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